The present invention relates to an exhaust tube, and more particularly to one have a better silencing effect.
Conventionally, an exhaust pipe for a car, as shown in FIGS. 1 and 4, includes an exhaust manifold 1 fixed to an engine, one or two straight type silencing tubes 2 (2A), a separating type silencing tube 3, and a plurality of connecting pipes in order to discharge the exhaust gas into the environmental atmosphere. Straight type silencing tube 2, as shown in FIG. 2, includes a tube body 4 having two end plates and a cylindrical iron piece 5, and a central pipe 6 connected to and passing through the end plates and having perforations 7 which enable that shocking sound waves of the shocking exhaust gas will counteract with each other in the hollow portion of tube body 4 through a resonating effect occurring therein. Such tube 2 does not provide any resistance against the exhaust gas flow since central pipe 6 is straight. Although it does not adversely affect the operation or the horsepower output of the engine, it does not have a good silencing effect. In order to cope with this problem, the separating type silencing tube 3 is added to the exhaust pipe assembly.
Separating type silencing tube 3, as shown in FIG. 3, includes a tube body 8 having two end plates, two spaced separating disks 9, 10 respectively having communicating slots 11, 12, and two guiding pipes 13, 14 which are respectively mounted on the two end plates, respectively have one ends thereof closed by disks 9, 10 and respectively include in tube body 8 perforations 15, 16, so that the exhaust gas will pass from pipe 13, through perforations 15, slots 11, slots 12, perforations 16, and then pipe 14, into the atmosphere. Such separating type tube 3 can effectively cancel the shocking sound waves of the shocking exhaust gas to achieve a better silencing effect, however, it produces a substantial resistance against the exhaust gas flow to reduce the engine horsepower output which can be evidenced by the fact that if silencing tube 3 is taken off, the engine horsepower output is greatly increased.